Colibacillosis is a common systemic disease of economic importance in poultry and occurs worldwide. This Escherichia coli (E. coli) infection occurs as an acute fatal septicemia or subacute pericarditis and airsacculitis, as well as perihepatitis, arthritis, and also cellulitis. Among bacterial infections, colibacillosis is very often the first cause of morbidity and mortality in poultry. Large numbers of E. coli are maintained in the poultry house environment through fecal contamination. Systemic infection occurs when large numbers of pathogenic E. coli gain access to the bloodstream via the respiratory tract or intestine. Bacteremia progresses to septicemia and death, or the infection extends to serosal surfaces, pericardium, joints and other organs.
The literature suggests that serotypes O1, O2 and O78 of E. coli associated with colibacillosis are the most common serotypes found in chickens and turkeys. Many isolated strains are also untypeable and are considered especially virulent.
Treatment strategies include control of predisposing infections or environmental factors, and early use of antibiotics. Unfortunately, a high frequency of resistance to tetracycline, kanamycin, neomycin, cephalotin, streptomycin and erythromycin has been observed. Many strains are also resistant to several antibiotics. Wide spread sensitivity to ampicillin and chloramphenicol has also been observed.
Although there is a commercial live E. coli vaccine available for use against colibacillosis associated with infection by E. coli O78 in turkeys, there appears to be no fully safe and effective E. coli vaccines for use in chickens. In particular, there does not appear to be any live, attenuated, mutant aroA gene-deleted E. coli vaccine for poultry commercially available. There also does not appear to be an especially efficacious E. coli vaccine that is suitable for mass administration via aerosol spray or drinking water, for example.
Therefore, it is an object of this invention to provide a safe and effective live E. coli vaccine, suitable for use in chickens.
It is another object of this invention to provide a method for the prevention or amelioration of colibacillosis in poultry which is safe and effective when used in chickens.
It is a feature of this invention that the E. coli vaccine is suitable for mass application.
It is an advantage of this invention that the live vaccine provides both a good cellular and a good humoral immunity response in the host.